It has long been recognized to be medically desirable to intravenously infuse liquid into and to sample blood from a patient. Certain problems have, nevertheless, persisted over the years in the fields of intravenous (IV) infusion and acquisition of blood specimens.
Typically, during delivery of IV solution to the patient through a cannula, such as a catheter tube or IV needle, it is difficult to predict when the supply of IV solution will become exhausted and even more difficult to coordinate availability of nursing personnel with the need to timely disconnect a soon-to-be-dry IV supply from the catheter tube or needle. As a consequence, the distal tip of the cannula sometimes experiences bleedback and clotting. More specifically, in a conventional IV hook-up to a patient, the flow of IV solution occurs because the force of gravity upon the solution exceeds the blood pressure in the cardiovascular system of the patient. When the supply of IV solution is exhausted, the pressure difference changes so that the cardiovascular pressure prevails, causing blood flow into the IV catheter tube a distance which may vary. Sometimes this blood flow reaches, contaminates and requires replacement of the IV filter. In any event, whether blood in the catheter will, within a short time, clot. This risks negligent introduction of the clot into the bloodstream and requires replacement of the IV system, when discovered.
Also, shifting of positions by the patient, as, for example, if the patient raises the venipuncture site above the IV bottle, sometimes causes refluxing or bleedback of blood into the distal end of the cannula. This reflux may or may not reach the IV filter, but in either event causes IV flow to stop which results in clotting within either the cannular, the filter or both.
When and if discovered, both the clotted IV filter and catheter tubes are replaced with the accompanying patient trauma and expense. It is bad practice and an unacceptable risk to the patient to force a clot from the catheter tube into the bloodstream, but, due to negligence, this sometimes happens.
It has been proposed that a one-way outdwelling (outside the patient) standard valve be used to prevent undesired blood flow into the distal end of an indwelling cannula, such as a catheter tube or IV needle. However, this approach does not work in a medically-acceptable fashion. Also, the one-way standard valve will not allow blood sampling when the standard one way valve is located between the catheter tube and the sampling site.
BRIEF SUMMARY AND OBJECTS OF THE INVENTION
In brief summary, the present invention overcomes or substantially alleviates the aforesaid problems. The invention comprises novel outdwelling, normally-closed, pressure-responsive medical slit valve liquid flow controls, and related methods, accommodating flow of liquid including, but not limited to, flow of IV solution to the cardiovascular system of a medical patient through a cannula, the distal end of which is indwelling, while preventing bleed-back into and clotting within the cannula and/or IV filter. Thus, cannula and IV filter replacement due to such clotting is obviated. The pressure responsive nature of the slit valve structure prevents the IV system from running dry. Consequently, clots do not form in the cannula and cannot inadvertently be introduced into the bloodstream.
Stated another way, the present invention provides a pressure-sensitive valve that opens in response to the high pressure exerted by a full IV solution bag or bottle but closes as the pressure drops as the bag or bottle empties, which solves or greatly reduces the problem of shutting off the IV flow when the bag or bottle runs dry. The valve opens and achieves adequate flow in response to a predetermined pressure differential, but closes after the pressure drops to a lower predetermined pressure differential.
The present invention accommodates configuration as a two-way valve that opens in either direction at the same or at different pressure differentials, and to allow IV solution in a gravity bag or bottle to flow, shuts off under pressure differential conditions which occur when the IV solution bag or bottle runs dry and yet allows intentional blood sampling across the valve.
Thus, in one presently preferred manifestation of the present invention, the slit valve accommodates bi-directional liquid flow by which both liquid ingress and blood sampling egress proximal of the slit valve are achieved. It is sometimes desirable for a two-way slit valve flow control embodying the present invention to allow distal flexing to open the slit for ingress flow at a relatively low pressure differential and proximal flexing to open the slit for egress flow at a relatively high pressure differential.
In a broad sense, the present invention contemplates provision of an outdwelling, normally closed pressure responsive slit valve by which liquid is selectively communicated to and from a desired internal body site.
Accordingly, it is a primary object of the present invention to overcome or substantially alleviate some if not all of the above-mentioned medical liquid flow control problems.
It is a further significant object to provide a novel outdwelling, normally-closed, pressure-responsive slit valve liquid flow control for use with a medical cannula, and related methods.
Another dominant object is the provision of an outdwelling slit valve structure, and related methods, accommodating flow of liquid, such as IV solution, to the cardiovascular system of a medical patient through a cannula, such as a peripheral catheter tube, a central venous catheter tube, an arterial catheter tube, or an IV needle, while preventing bleed-back into and clotting within the cannular and obviating any resulting need for cannula and IV filter replacement.
A further important object is the provision of noval outdwelling, cardiovascular slit valve structure, and related methods, which prevents an associated IV system from running dry.
An additional principal object of the present invention is the provision of novel outdwelling, two-way slit valve structure, and related methods, for use in achieving selective ingress and egress liquid flow in respect to a desired internal body site of a patient. A further object of significance is the provision of a novel outdwelling two-way normally closed slit valve, and related methods, in which the slit valve is distally flexed, due to a first predetermined pressure differential, to accommodate intentional fluid flow to a desired internal location in a patient, is closed, due to a second predetermined pressure differential, and is proximally flexed, due to a third pressure differential, to accommodate intentional fluid flow from the internal location in the patient.
Another valuable object is the provision of a novel outdwelling two-way cardiovascular normally closed slit valve, and related methods, in which the slit valve is distally flexed to open a slit for flow to a patient at a relatively low pressure differential across the slit valve and is proximally flexed to open the slit for flow away from the patient at a relatively high pressure differential across the slit valve.
An additional object is the provision of an outdwelling, normally closed slit valve by which liquid is selectively communicated to and from a desired internal body location of a medical patient.
These and other objects and features of the present invention will be apparent from the detailed description taken with reference to the accompanying drawings.